An important area for application of diagnostic imaging methods is in staging of colorectal cancers. Computed tomography (CT), magnetic resonance imaging (MRI), transrectal ultrasonography (TRUS), radionuclide imaging and positron emission tomography (PET) have important roles in the detection of local invasion, and lymphatic or hematogenous dissemination of colorectal neoplasms. The aim of this proposal is to join a collaborative multicenter group to compare the sensitivity and specificity of several diagnostic imaging methods in the preoperative staging of colorectal tumors. Patients examined at the Mallinckrodt Institute of Radiology, to include those with operated colorectal tumors, will be imaged with CT, TRUS and/or MRI. The results will be subjected to statistical analysis to assess the relative accuracy and specificity of each imaging methods. In the second part of the proposal, a protocol is described wherein patients who are considered for liver resection because of isolated hepatic metastases from colorectal cancer will be studied with CT, computed tomographic atrial portography (CT-AP), and MRI within 3 weeks of operation. The resected liver will be sectioned axially at 1 cm intervals and the number, size and location of lesions will be carefully documented and correlated with all imaging methods for direct validation.